Such is Ronaldo's bond with United it has even be suggested that the Premier League leaders could look to tempt the 28-year-old to return to Old Trafford this summer, with the clubs preparing to face off in the Champions League on Tuesday.

Ferguson was most likely accurate in assessment that United are being used as a bargaining tool by Ronaldo’s advisors, the United boss saying it would be “false hope” to expect the Portuguese to return to Old Trafford.

"There hasn't been anything to encourage me to think Cristiano would come back here," said Ferguson.

"As far as I am aware, there is nothing in it at all. Ronaldo has got two years left on his contract and it seems to me it is all part of the negotiations that are going on about a new deal.

"Maybe his agent is playing the game. I think it is false hope. Cristiano will get a good reception. All our former players, especially the ones who have been great for this club, get a good reception when they return."

And while Ferguson's pessimism is well-founded, United's close association with Ronaldo's agent Jorge Mendes leaves the club fully aware of the current state of play surrounding the Madrid star.

The likelihood is that Ronaldo would cost a transfer fee approaching €115 million in addition to a salary of as much as €462,000-a-week - a huge stretch for even a club with United’s €347m-plus revenues.

United would probably have to sell at least one key player to free transfer funds and wage budget to finance a deal for Ronaldo.

Nani is likely to leave for around €17m this summer, with one year left on his contract, but Wayne Rooney could hold the key. The striker is himself out of contract in 2015 and, amid interest from big-spending Paris Saint-Germain, is the club’s most valuable playing asset.

Whether Rooney would be interested in a move to the French capital is unknown, but his importance at United has been diminished since the arrival of Robin van Persie and he will not be offered an increase on his current €289,000-a-week salary to sign a new deal.

For all his ego, Ronaldo is a sensitive and sentimental character. He has spoken about the emotion of returning to Old Trafford and is using his time in Manchester to meet friends and visit his old home in leafy Alderley Edge.

Ferguson and his players have launched a charm offensive ever since the Champions League last 16 draw pitted them against their former star, with the tie finely balanced heading in to Tuesday night’s second following a 1-1 draw at the Santiago Bernabeu.

Ronaldo will receive a hero’s welcome from the crowd on his first return to Old Trafford and if, as has been suggested, he feels unappreciated in Madrid, Patrice Evra says United will try to “kill him with love”, to take the edge off his game and make him feel sentimental.

Ronaldo, who has scored a stunning 185 goals in 184 appearances, would jump at the chance to re-join United if he decides to leave Real Madrid, and while the finances would make the deal difficult, the Premier League leaders would explore every avenue to make it happen.

There is no doubt that United are inside Ronaldo’s head and his heart at the moment. After the first leg last month, in which the he scored Real Madrid’s equaliser with a soaring header, Ronaldo spent half-an-hour in the United dressing room catching up with former team-mates.

Ronaldo is still in regular touch, largely via text message, with a number of United players while he has spoken comprehensively about his father-and-son relationship with Ferguson, who signed him from Sporting Lisbon as a talented but raw winger in in 2003.

When the Real Madrid touched down in Manchester on Sunday, Ronaldo was greeted by a gaggle of United fans seeking autographs and holding placards calling for him to ‘come home’.

The cynic might suggest that Ferguson is operating mind games, knowing that Ronaldo is the type of personality who thrives under pressure, as he proved once again last week as he scored twice in Real Madrid’s Copa del Rey win at bitter rivals Barcelona.

But Ferguson knows Ronaldo better than most. Until the player commits his future to Real Madrid by signing a new contract, the charm offensive will continue, the subtle suggestions disseminated that Manchester is the Portugal captain’s spiritual home.

United have proven in the recent past that they can pull off seemingly unlikely deals, not least in convincing Rooney to perform a U-turn and sign a new contract in 2010 and beating rivals Manchester City to land Van Persie last summer.

A return to United for Ronaldo looks highly unlikely at the moment, but rest assured it would be a dream signing for Ferguson - and, perhaps, the player himself.